A foul stench from an unknown source has plagued Carson residents near the Dominguez Channel for nearly two weeks now, sickening some, and county officials on Friday began working to eliminate the odor.

Several Los Angeles County agencies have been investigating the pungent smell since Oct. 6, including the South Coast Air Quality Management District. But the cause has been elusive, and Carson City Council declared the stench a public nuisance.

Residents describe it as an overwhelming stench like hydrogen sulfide or rotten eggs. This week, some also began noticing discolored, foul-smelling water coming out of their drains.

On Saturday, Los Angeles County Public Works confirmed that there is “no connection” between the odor coming from the Dominguez Channel and the brown water.

Instead, Public Works attributed the brown water to come from “sanitary sewer backups at two private residences.”

“Closed-circuit cameras were used to inspect the underground mainline sewer infrastructure maintained by the County and no issues or blockages were found,” the statement read.

On Friday, L.A. County public works staff started spraying Epoleon, a biodegradable deodorizer, into the channel to help diminish the smell. Officials say the product is water-based and made with natural, non-toxic compounds.

Next week, a dozen aeration devices will be installed to inject a multitude of tiny bubbles into the channel, which should increase its dissolved oxygen levels over the course of three months.

More oxygen should speed up the decomposition of any organic matter in the channel — which may cause odor issues to peak for a short time, but officials say the deodorizing product should decrease that impact.

Although the estuary occasionally stinks, Carson Mayor Lula Davis-Holmes said “the odor never lasts this long. I’ve been here for 40 years.” 

Davis-Holmes said she’d been told the smell could be connected to a massive fire at a warehouse in Carson on Sept. 30 after some charred cardboard made its way into the channel. 

If the process goes according to plan, Davis-Holmes said the smell should go away in five days. 

Residents have reported symptoms including headaches, nausea and upper-respiratory irritation. Brandy Williams Murdoch, who lives in the area, said even people’s pets have been sickened by the stench.

Williams Murdoch said she can’t believe it’s taken this long for officials to address the odor. 

“We need help,” she said. “I am shouting it from the rooftops.” 

Due to the negative health impacts, L.A. County public health officials are recommending residents limit exposure to their families and pets. That can mean keeping doors and windows closed, checking air filters, and even relocating to another area.

U.S. Rep. Nanette Barragan, who represents the area, says she’s asked Gov. Gavin Newsom to declare a state of emergency surrounding the situation. 

“I was very concerned when I heard back from the EPA that this is just an odor,” she said. “This is not just an odor. It’s a public health emergency.” 

The county also has a reimbursement program for residents and businesses affected. This includes those who have had to pay for hotel rooms, and those who don’t have access to a portable indoor air filter or an HVAC system that can be equipped with a HEPA or MERV-rated filters with activated charcoal.

The assistance is currently being offered through Oct. 21. Residents should contact the County’s 211 help line for information and assistance with submitting a reimbursement request, or visit lacounty.gov/emergency/dominguez-channel.

Community outreach staff with the county’s Public Works Department will also be at the Carson Community Center seven days a week, from 7:30 a.m. to 6:30 p.m. to answer questions and assist with the reimbursement process.

To file a complaint about odors in the air, call AQMD at 800-288-7664 or visit aqmd.gov/home/air-quality/complaints.